Choke control device



Oct. 24, 1967 3 H. J. UMPFENBACH 3,348,530

CHOKE CONTROL DEVICE 2 She etsSheet 1 Filed Aug 2, 1965 INVENTOR.

HERMAN J. UMPFENBACH BY 2 v Z FIG.

ATTORNEYS v1967' H. .1. UMP'FENBACH 3,348,530

CHOKE CONTROL DEVICE 2 Sheets-Sheet 2 Filed Aug. 2, 1965 INVENTOR HERMAN J. UMPFENBACH FIG.'5

TTORNEYS United States Patent 1 3,348,530 CHOKE CONTROL DEVICE Herman J. Umpfenbach, Detroit, Mich., assignor to The Bendix Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 2, 1965, Ser. No. 476,270 8 Claims. (Cl. 123-119) ABSTRACT OF THE DISCLOSURE A choke control device for an engine carburetor having a collar secured to an offset choke valve shaft, a lever connected to an engine temperature responsive member engaging the collar to urge the choke valve. toward the closed position, and an extension formed on the collar adapted to engage the lever for positively holding the choke valve in the closed position until the engine becomes self-operative.

The present invention relates to an automatic choke, and more particularly to a device for locking the choke valve in closed position while the engine is being started.

In conventional automotive and small air cooled engine carburetors, the choke valve is offsetand spring loaded so that the air flow created upon firing of the engine will open the valve suflficiently to provide the required air to sustain operation. However, in order to provide the required air during the initial self-operation of the engine, the offset valve and spring loading relationship must be such that the choke valve will be opened with relatively little air flow until the engine is operating normally. In many engines, however, the suction created during cranking is sufficient to cause the choke valve to open and thereby reduce the richness of the fuel-air mixture to the point where the cold engine cannot be started. This difiiculty cannot be effectively corrected by adjusting the relationship of the spring force urging the valve closed and the degree of offset of the valve, since the degree of suction created during the cranking operation and during the initial self-operation of the engine may be substantially the same, or the difference too small to permit effective and reliable adjustment to obtain proper choking during cranking and initial running of the engine. It is therefore one of the principal objects of the present invention to provide a mechanism for controlling the operation of an offset spring-loaded choke valve, which effectively retains the choke valve in closed position while the engine is being cranked to give the proper enriched starting mixture, and then immediately partially releases the choke valve when the engine starts to give the required air for sustaining engine operation.

Another object of the invention is to provide an automatic choke control device which holds the choke in closed position regardless of the cranking speed of the engine or the degree of vacuum created during starting, and which controls the choke after starting to give the required enriched mixture until the normal operating temperature of the engine has been reached.

Still another object of the invention is to provide a relatively simple, reliable choke control device of the pneumatic type which effectively provides the required enriched mixture during cranking and thereafter varies the opening of the choke valve in accordance with engine temperature and operating conditions to give the required fuel-air mixture through the warming up period, of the engine.

Afurther object is to provide an automatic choke device which can be readily adapted to various engines and adjusted to satisfy the starting requirements from one engine to another, and which will perform satisfactorily under various operating conditions without manual adjustment or control.

Additional objects and advantages of the invention will become apparent from the following description and accompanyingdrawings, wherein:

FIGURE 1 is a front elevational view of a carburetor with the present automatic choke control device mounted thereon in operative position;

FIGURE 2 is a side elevational view of the carburetor and choke control device shown in FIGURE 1;

FIGURE 3 is an enlarged fragmentary cross sectional view of the choke control device, the section being taken on line 3-3 of FIGURE 1; FIGURE 4 is an enlarged fragmentary cross sectional view of a portion of the carburetor and choke control linkage, illustrating the manner in which the device operates, the section being taken on line 44 of FIGURE 2; and

FIGURE 5 is an elevational view of the choke control linkage shown in the preceding figures.

Referring more specifically to the drawings, numeral 10 designates generally a carburetor and 12 the pneumatic automatic choke embodying the present invention. For the purposes of the present description, carburetor 10 may be considered a conventional float type carburetor, consisting of body 14 having an inductor passage with an air inlet 16, a fuel-air mixture outlet 18, and a float chamber 20 disposed beneath and supported by carburetor body 14. A throttle (not shown) is disposed in the induction passage on throttle shaft 22 controlled manually by a suitable linkage connected to lever 24. The fuel is supplied to the float chamber through valve 26 and is discharged in the induction passage through a main discharge nozzle (not shown) and through an idle system controlled by valve 28.

A choke valve 30 is mounted on shaft 32, offset with the larger portion of the valve above shaft 32, and is secured to the shaft for rotation therewith by screws 34 and 36 extending through the valve and threaded into shaft 32. The shaft is journalled in bosses 38 and 40 and extends laterally to the left, as viewed in FIGURES 1 and 4, for receiving the operating mechanism of the automatic choke. Valve 30 is urged toward closed position by a coil spring 42 mounted on shaft 32 and connected at one end to a pin 44 seated in a boss 46 of carburetor body 14, and at the other end to a collar 48 rigidly secured to the end of shaft 32 by set screw 50 so that the collar and shaft rotate in unison. The choke valve, being offset with respect to the induction passage, is urged in the open direction by vacuum in the induction passage downstream from the choke valve and the opening thereof is opposed, under certain conditions hereinafter described, by spring 42 reacting between collar 48 and pin 44.

The choke control device 12 includes a pneumatic unit 60 consisting of a housing 62 having sections 64 and 66 secured together by a plurality of screws 68 extending through holes in the margins of section 66- and threadedly seating in holes .in the margins of section 64, unit 60 being supported on the side of the'carburetor body by a bracket 63 secured thereto by one of the screws 68. A fluid-impervious diaphragm 70 is secured at its marginal edge between housing sections 64 and 66 in fluid-tight relation, thus forming two separate chambers 72 and 74 on the left and right-hand sides thereof, as viewed in FIGURE 3. The diaphragm is reinforced by stiffening plates 76 and 78 on the right and left sides of the diaphragm, and is urged toward chamber 72 by a coil spring 80 reacting between stiffening plate 76 and the inner end wall of section 66, chamber 74 being vented to ambient air by one or more ports 82 in the wall of section 66. A stem 86 extends through the center of diaphragm 70 and is secured thereto by outwardly extending annular flanges 90 and 92 which rigidly clamp reinforcing plates 76 and 78 against the diaphragm to form an effective seal between the diaphragm, stern and plates, and extends through opening 88 in the end of section 66 and projects outwardly therefrom for connection with the choke linkage, to be more fully described hereinafter. Chamber 72 is connected by a tube 94 and conduit 96 in stem 98 to a bulb 99 located in the exhaust passage or manifold. The bulb, tube 94, passage 96 and chamber 72 form, in effect, a closed chamber, filled with a gas which expands as the manifold temperature rises and urges diaphragm 70 to the right, as viewed in FIGURE 3, moving stem 86 axially to the right from the position shown in full lines to the position shown in broken lines.

Stern 86 is connected to collar 48 by a linkage consisting of a lever 100 pivoted at its lower end on pin 101 rigidly supported by two bosses 102 and 103. The lever is connected to a collar 106 mounted for relative rotation on the end of shaft 32 by a pin 108 rigidly secured at one end to collar 106 and at the other end slidably positioned between the main portion 110- of lever 100 and an overlapping portion 111 of the lever, the collar being retained on the shaft by a washer 112 and a pin 113 extending through the shaft. Pin 108 is adapted to slide in the space between the main portion 110 and the overlapping portion 111 as the lever moves between the two positions illustrated in FIGURE 3, and thereby rotates collar 106. A one-way connection is provided between collars 48 and 106 by overlapping lug 114 on flange 116 of collar 106 and lug 118 on flange 120 of collar 48. Lug 114 engages lug 118 when the choke is responding to cold engine conditions and holds lever 100 in the position to close choke valve 30. Lever 100 is operatively connected to stem 86 by a reduced diameter portion 122 of stem 86 seating in a slot 124 of lever 100, the larger diameter portion of stem 86 on opposite sides of portion 122 forming abutments for engaging the lever on either side of slot 124 and for pivoting the lever angularly, a illustrated in FIGURE 3. An enlarged opening 126 at the upper end of slot 124 is provided to permit the reduced diameter portion 122 to be inserted in the slot.

In order to retain the choke valve in closed position during cranking, a positive stop mechanism is used consisting of an extension 130 rigidly connected to collar 48 and extending laterally to a position in the line of angular movement of the upper end of lever 100. An adjustment screw 132 is threadedly received in a hole 134 in the outer end of extension 130 for engaging the upper end 136 of lever 100, a coil spring 138 on screw 132 being used to retain the screw in any adjusted position. When the end of screw 132 is in engagement with the upper end of lever 100, shaft 32 and collar 48 to which lever 130 is rigidly secured are positively held in the closed choke position, thus preventing the offset choke valve 30 from being opened by the suction created during cranking. Lever 100 remains in the position shown in full lines in FIGURE 3 until the engine starts, and as soon as the engine fires and the gas in tube 94 and chamber 72 expands, the lever is moved by diaphragm 70 and stem 86 from beneath screw 132, permitting rotation of collar 48 and shaft 32 in the direction to open the choke valve.

In the operation of the present choke control device, starting with a cold engine, the pressure in the temperature sensitive bulb 99, tube 94 and chamber 72 is of such volume that spring 80 holds the diaphragm, and consequently stem 86, in the position shown in full lines in FIGURE 3. With stem 86 in this position, lever 100, collar 48 and lug 114 are likewise in the positions shown in full lines in FIGURES 1 and 3, lug 114 being in contact with lug 118, thereby holding collar 48 and shaft 32 in their full clockwise position, as viewed in FIGURES l and 2. With the linkage in this position, choke valve 30 is 4 yieldably held in closed position. While the engine is being cranked with the linkage in this position, screw 132 is seated on upper end 136 of lever and through extension prevents collar 48 and shaft 32 from rotating, and thus positively holds choke valve 30 in its closed position regardless of the vacuum created during cranking. The choke unit, linkage and throttle valve remain in this position throughout cranking.

As soon as the engine fires and the heat in the exhaust pipe or manifold heats bulb 99, the gas therein expands, moving diaphragm 70 and stem 86 to the right, as viewed in FIGURE 3, thus moving lever 100 in the clockwise direction. When the lever moves from beneath screw 132, collar 48 and shaft 32 are free to rotate in the counterclockwise direction, thus permitting the choke valve 30 to respond to the vacuum created by the running of the engine and to be opened thereby to varying degrees as determined by the amount of vacuum. This choke releasing and opening operation is performed rapidly after the engine begins to fire; however, the pressure in chamber 72 which varies with the temperature of the bulb in the exhaust pipe or manifold, assists in holding the choke valve at various intermediate positions between closed and open positions until the engine has reached proper operating temperatures. When the engine is warm as sensed by the bulb in the exhaust pipe or manifold, stem 86 and lever 100 are held in the position shown in broken lines in FIG- URE 3 and the choke valve is in fully opened position, i.e. in horizontal position as illustrated in FIGURE 4.

The present choke control device can be effectively used in conjunction with other types of automatic chokes, including the bimetallic and vacuum types. While only one embodiment of the present device has been described in detail herein, various changes and modifications may be made to satisfy requirements.

I claim:

1. A choke control device for a carburetor having a body, an induction passage, a shaft, and an offset choke valve mounted on the shaft, and for an engine having an exhaust passage, comprising a unit responsive to engine temperature for controlling the choke valve incl-uding a housing with a chamber, a movable wall for said chamber, a bulb in the engine exhaust passage, a conduit connecting said bulb with said chamber, a stern movable axially by said movable wall, a pivoted lever movable angularly by said stem, a collar rigidly mounted on the choke valve shaft for rotation therewith, a coil spring mounted on said shaft and anchored at one end to said body and at the other end to said collar urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, lugs on said collars forming a one-way connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar for engaging said lever when said lever is in cold engine position and thereby positively holding said collar in position to lock the choke valve in closed position.

2. A choke control device for a carburetor having a body, an induction passage, a shaft, and an offset choke valve mounted on the shaft, and for an engine having an exhaust passage, comprising a unit responsive to engine temperature for controlling the choke valve including a housing with a chamber, a movable wall for said chamber, a bulb in the engine exhaust passage, a conduit connecting said bulb with said chamber, a stem movable axially by said movable wall, a pivoted lever movable angularly by said stem, a collar rigidly mounted on the choke valve shaft for rotation therewith, a spring on said shaft urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, means on said collars forming a one-way connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar for engaging said lever when said lever is in cold engine position and thereby holding said collar in position to lock the choke valve in closed position.

3. A choke control device for an engine carburetor having a body, an induction passage, a shaft, and an 0&- set choke valve mounted on the shaft, comprising a unit responsive to engine temperature for controlling the choke valve including a housing with a chamber, a movable wall for said chamber, a stem movable axially by said movable wall, a pivoted lever movable angularly by said stem, a collar rigidly mounted on the choke valve shaft for rotation therewith, a coil spring mounted on said shaft and anchored at one end to said body and at the other end to said collar urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, lugs on said collars forming a oneway connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar for engaging said lever when said lever is in cold engine position and thereby holding said collar in position to lock the choke valve in closed position.

4. A choke control device for an engine carburetor having a body, an induction passage, a shaft, and an offset choke valve mounted on the shaft, comprising a unit responsive to engine temperature for controlling the choke valve including a housing with a chamber, a movable Wall for said chamber, a stem movable axially by said movable wall, a pivoted lever movable angularly by said stem, a collar rigidly mounted on the choke valve shaft for rotation therewith, a spring on said shaft urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, means on said collars forming a one-way connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar for engaging said lever when said lever is in cold engine position and thereby holding said collar in position to lock the choke valve in closed position.

5. A choke control device for an engine carburetor having a body, an induction passage, a shaft, and an offset choke valve mounted on the shaft, comprising a unit responsive to engine temperature for controlling the choke valve with an axially movable stem, a pivoted lever movable angularly by said stem, a collar rigidly mounted on the choke valve shaft for rotation therewith, a coil spring mounted on said shaft and anchored at one end to said body and at the other end to said collar urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, lugs on said col lars forming a one-way connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar for engaging said lever when said lever is in cold engine position and thereby holding said collar in position to lock the choke valve in closed position.

6. A choke control device for an engine carburetor having a body, an induction passage, a shaft, and an offset choke valve mounted on the shaft, comprising a unit responsive to engine temperature for controlling the choke valve including a movable member, a pivoted lever movable angularly by said member, a collar rigidly mounted on the choke valve shaft for rotation therewith, a spring urging said vave toward closed position, a sec- 0nd collar mounted on said shaft for relative rotation with respect to said shaft, means on said collars forming a one-way connection for closing the choke valve, means connecting said second collar to said lever, and an extension connected to said first collar 'for engaging said lever when said lever is in cold engine position and thereby holding said collar in position to lock the choke valve in closed position.

7. A choke control device for a carburetor having a body, an induction passage, a shaft, and an olfset choke valve mounted on the shaft, comprising a unit responsive to'engine temperature for controlling the choke valve including a movable member, a pivoted lever movable angularly by said member, a collar rigidly mounted on the choke valve shaft for rotation therewith, a spring urging said valve toward closed position, a second collar mounted on said shaft for rotation relative to said shaft, means on said collars forming a one-way connection for closing the choke valve, means controlled by said movable member for holding said choke valve in closed position.

8. A choke control device for a carburetor having a body, an induction passage, a shaft, an offset choke valve mounted on the shaft, and a spring urging said valve toward the closed position, comprising a unit responsive to engine temperature for controlling the choke valve in cluding a movable member, collar means on said shaft for rotation therewith, lever means movable by said member to engagesaid collar means to urge said choke valve toward the closed position, and extension means formed on said collar means for engaging said lever means for positively holding said choke valve in the closed position regardless of engine manifold vacuum until said lever means is moved out of engagement with said extension means by said movable member.

References Cited UNITED STATES PATENTS 1,996,245 4/1935 Hunt 123-119 I 2,226,580 12/1 940 Perrine 123119 2,774,343 12/1956 Schaifer et al 26139 X 2,995,348 8/1961 Eberhardt 26139 2,998,233 8/1961 Marsee 26139 3,185,453 5/1965 Mennesson 123119 X AL LAWRENCE SMITH, Primary Examiner. 

8. A CHOKE CONTROL DEVICE FOR CARBURETOR HAVING A BODY, AN INDUCTION PASSAGE, A SHAFT, AN OFFSET CHOKE VALVE MOUNTED ON THE SHAFT, AND A SPRING URGING SAID VALVE TOWARD THE CLOSED POSITION, COMPRISING A UNIT RESPONSIVE TO ENGINE TEMPERATURE FOR CONTROLLING THE CHOKE VALVE INCLUDING A MOVABLE MEMBER, COLLER MEANS ON SAID SHAFT FOR ROTATION THEREWITH, LEVER MEANS MOVABLE BY SAID MEMBER TO ENGAGE SAID COLLAR MEANS TO URGE SAID CHOKE VALVE TOWARD THE CLOSED POSITION, AND EXTENSION MEANS FORMED ON SAID COLLAR MEANS FOR ENGAGING SAID LEVER MEANS FOR POSITIVELY HOLDING SAID CHOKE VALVE IN THE CLOSED POSITION REGARDLESS OF ENGINE MANIFOLD VACUUM UNTIL SAID LEVER MEANS IS MOVED OUT OF ENGAGEMENT WITH SAID EXTENSION MEANS BY SAID MOVABLE MEMBER. 